Re: FYI: Load times for a largish DB in 8.2 vs. 8.3 vs. 8.4

Tom Lane wrote:
> "Todd A. Cook" <tcook(at)blackducksoftware(dot)com> writes:
>> First, the numbers:
>
>> PG Version Load time pg_database_size autovac
>> ----------------------------------------------------------
>> 8.2.13 179 min 92,807,992,820 on
>> 8.3.7 180 min 84,048,744,044 on (defaults)
>> 8.4b2 206 min 84,028,995,344 on (defaults)
>> 8.4b2 183 min 84,028,839,696 off
>
>> The bulk of the data is in 16 tables, each having about 55 million rows of
>> the form (int, int, smallint, smallint, int, int, int). Each table has a
>> single partial index on one of the integer columns.
>
> Given that it's multiple tables, it'd be possible for autovacuum to
> kick in and ANALYZE the data inserted into earlier tables while the
> later ones were still being loaded. If so, the discrepancy might be
> explained by 8.4's more-aggressive statistics target, which means that
> a background ANALYZE will take about 10x more work than before.
>
> If you have time to repeat the experiments, it would be interesting to
> see what happens with consistent default_statistics_target across 8.3
> and 8.4.

That would seem to be it:

8.4b2 183 min 84,028,897,040 on (defaults, default_statistics_target=10)

I'll run the test on 8.3.7 with default_statistics_target=100 over the weekend.

-- todd

>
> regards, tom lane
> .
>